SEASONAL DYNAMICS OF CHEMICAL AND MICROBIOLOGICAL CHARACTERISTICS OF BOTTOM SEDIMENTS IN THE SEA ESTUARY OF A SMALL RIVER IN THE SEVASTOPOL REGION (BY THE EXAMPLE OF THE CHERNAYA RIVER, CRIMEA)

Abstract

The annual dynamics of (1) chloroform-extractable substances (CES) and petroleum hydrocarbons (PH) in riverside fluvial sediments, in the bottom sediments of the mixing zone of river and sea waters, and in the bottom sediments of the marine area, and (2) the abundance of hydrocarbon-oxidizing (HOB) and heterotrophic (HB) bacterial groups in the bottom sediments of the marine area and riverside sediments is analysed. The maximal content of CES was found in the marine area (450±17.5 mg/100 g), and the minimal one - in the river part (127.6±10.9 mg/100 g), in the mixing zone of river and sea waters - 370±37.9 mg/100 g. The average concentrations of PH are distributed similarly to the concentrations of CES: the maximal values (127.5±10.9 mg/100 g) are detected in marine ground, the values for the sediments of the mixing zone are slightly lower (103.1±9.4 mg/100 g), and the minimal values (54.8±23.9 mg/100 g) are detected in river sediments. The physicochemical characteristics of bottom and coastal sediments are presented. The abundance of HB in the bottom sediments of the marine area varied from 7.5•103 to 2.5•106 cells/g, respectively, and from 9.5•103 to 9.5•108 cells/g in the river area. There was no seasonal variability in the abundance of HB at both areas. Hydrocarbon-oxidizing bacteria were registered in 100 % of the samples of bottom and riverside sediments of the designated water areas. The abundance of HOB varied from 25 to 2.5•104 cells/g in the marine zone and from 25 to 4.5•103 cells/g in the river zone. The maximal values of HOB abundance in the riverside sediments were recorded during the flood period (February-April).